"""
Bifacial Modeling - procedural
==============================

Example of bifacial modeling using pvfactors and procedural method
"""

# %%
# This example shows how to complete a bifacial modeling example using the
# :py:func:`pvlib.pvsystem.pvwatts_dc` with the
# :py:func:`pvlib.bifacial.pvfactors.pvfactors_timeseries` function to
# transpose GHI data to both front and rear Plane of Array (POA) irradiance.
#
# .. attention::
#    To run this example, the ``solarfactors`` package (an implementation
#    of the pvfactors model) must be installed.  It can be installed with
#    either ``pip install solarfactors`` or ``pip install pvlib[optional]``,
#    which installs all of pvlib's optional dependencies.

import pandas as pd
from pvlib import location
from pvlib import tracking
from pvlib.bifacial.pvfactors import pvfactors_timeseries
from pvlib import temperature
from pvlib import pvsystem
import matplotlib.pyplot as plt
import warnings

# supressing shapely warnings that occur on import of pvfactors
warnings.filterwarnings(action='ignore', module='pvfactors')

# using Greensboro, NC for this example
lat, lon = 36.084, -79.817
tz = 'Etc/GMT+5'
times = pd.date_range('2021-06-21', '2021-06-22', freq='1T', tz=tz)

# create location object and get clearsky data
site_location = location.Location(lat, lon, tz=tz, name='Greensboro, NC')
cs = site_location.get_clearsky(times)

# get solar position data
solar_position = site_location.get_solarposition(times)

# set ground coverage ratio and max_angle to
# pull orientation data for a single-axis tracker
gcr = 0.35
max_phi = 60
orientation = tracking.singleaxis(solar_position['apparent_zenith'],
                                  solar_position['azimuth'],
                                  max_angle=max_phi,
                                  backtrack=True,
                                  gcr=gcr
                                  )

# set axis_azimuth, albedo, pvrow width and height, and use
# the pvfactors engine for both front and rear-side absorbed irradiance
axis_azimuth = 180
pvrow_height = 3
pvrow_width = 4
albedo = 0.2

# explicity simulate on pvarray with 3 rows, with sensor placed in middle row
# users may select different values depending on needs
irrad = pvfactors_timeseries(solar_position['azimuth'],
                             solar_position['apparent_zenith'],
                             orientation['surface_azimuth'],
                             orientation['surface_tilt'],
                             axis_azimuth,
                             cs.index,
                             cs['dni'],
                             cs['dhi'],
                             gcr,
                             pvrow_height,
                             pvrow_width,
                             albedo,
                             n_pvrows=3,
                             index_observed_pvrow=1
                             )

# turn into pandas DataFrame
irrad = pd.concat(irrad, axis=1)

# using bifaciality factor and pvfactors results, create effective irradiance
bifaciality = 0.75
effective_irrad_bifi = irrad['total_abs_front'] + (irrad['total_abs_back']
                                                   * bifaciality)

# get cell temperature using the Faiman model
temp_cell = temperature.faiman(effective_irrad_bifi, temp_air=25,
                               wind_speed=1)

# using the pvwatts_dc model and parameters detailed above,
# set pdc0 and return DC power for both bifacial and monofacial
pdc0 = 1
gamma_pdc = -0.0043
pdc_bifi = pvsystem.pvwatts_dc(effective_irrad_bifi,
                               temp_cell,
                               pdc0,
                               gamma_pdc=gamma_pdc
                               ).fillna(0)
pdc_bifi.plot(title='Bifacial Simulation on June Solstice', ylabel='DC Power')

# %%
# For illustration, perform monofacial simulation using pvfactors front-side
# irradiance (AOI-corrected), and plot along with bifacial results.

effective_irrad_mono = irrad['total_abs_front']
pdc_mono = pvsystem.pvwatts_dc(effective_irrad_mono,
                               temp_cell,
                               pdc0,
                               gamma_pdc=gamma_pdc
                               ).fillna(0)

# plot monofacial results
plt.figure()
plt.title('Bifacial vs Monofacial Simulation - June Solstice')
pdc_bifi.plot(label='Bifacial')
pdc_mono.plot(label='Monofacial')
plt.ylabel('DC Power')
plt.legend()
# sphinx_gallery_thumbnail_number = 2
